Composition for Chemical-Mechanical Polishing (Cmp)

ABSTRACT

A material which has a high removal rate with a simultaneously gentle polishing behavior is to be made available with a composition in the form of a dispersion or a slurry for the chemical-mechanical polishing (CMP) in the production of electronic or microelectronic components, in particular, semiconductor elements, and/or a mechanical component, in particular, a microelectromechanical component or semiconductor element (MEMS).  
     This is attained in that the composition contains titanium oxide hydrate particles with the approximation formula TiO 2 *xH 2 O*yH 2 SO 4 , wherein the H 2 O content of the titanium oxide hydrate particles is 4-25 wt %, preferably 2-10 wt %, and the H 2 SO 4  content is 0-15 wt %, preferably 0.1-10 wt %.

The invention concerns compositions in the form of a dispersion or aslurry for chemical-mechanical polishing (CMP) in the production ofelectronic or microelectronic components, in particular, semiconductorelements, and/or a mechanical component, in particular, amicroelectromechanical component or semiconductor element (MEMS).

Furthermore, the invention concerns a method for the production of anelectronic or microelectronic component, in particular, a semiconductorelement, and/or a mechanical component, in particular, amicroelectromechanical component or semiconductor element (MEMS), whichis subjected to a chemical-mechanical polishing process (CMP), under theinfluence of a titanium-containing composition in the form of adispersion or a slurry. It is also directed toward a microelectroniccomponent, in particular, a semiconductor element, and/or a mechanicalcomponent, in particular, microelectromechanical component orsemiconductor element (MEMS), produced according to this method.

Finally, the invention concerns a chemical-mechanical polishing (CMP)carried out by using the preceding composition.

The dispersion or slurry is a polishing liquid which is used inso-called chemical-mechanical polishing (CMP), which is also called achemical-mechanical planarization.

In modern integrated circuits (IC), a large number of microelectroniccomponents such as transistors, diodes, capacitors and the like areproduced on a substrate, for example, silicon or other semiconducting,insulating, or conducting materials. The circuits consist of structured,semiconducting, nonconducting, and electrically conductive thin layers.These structured layers are usually produced in that a layer material isapplied by physical or chemical means (for example, evaporation, cathodesputtering, chemical deposition from the vapor phase or somethingsimilar), and is structured by a microlithographic method. By thecombination of the different semiconducting, nonconducting, andconducting layer materials, the electronic circuit elements of the IC,such as transistors, capacitors, resistors and others, are defined andproduced.

These individual circuit elements must be connected with one another bymeans of a so-called metallization, in accordance with the requiredfunctionality of the integrated circuit. To this end, a so-calledintermediate level dielectric is deposited via the elements, and passageopenings in the dielectric layer are formed. Subsequently, thedeposition of the metal for the actual conducting paths is carried out.Two methods are usually used for the structuring of the metal. In afirst method, the metal, for example, aluminum, is structured with aphotolithographically applied lacquer mask by, for example, ion etching(RIE). In a second method, which is preferably used if the metal cannotbe etched by means of RIE, the passage openings and trenches etched intothe intermediate level dielectric are filled with metal, for example,copper or tungsten, in order to prepare the electrical connection of theindividual semiconductor elements (so-called damascene or dual-damascenemethod). Repolishing by means of chemical-mechanical polishing (CMP)leads to the metal-filled trenches or passage openings. As a result ofthe constantly increasing number of semiconducting elements and theimmense complexity of modern integrated circuits, a large number ofmetallization layers must typically be stacked on one another in orderto attain the required functionality.

Within the framework of an economical manufacturing of the integratedcircuits, the structural widths of the circuits are regularlyreduced—that is, the circuits are smaller and the substrate surface—thatis, the disk diameter (wafer diameter)—and thus the number of circuitson the wafer increases. The lithography methods used to attain thedesired structural widths—with the most modern ICs, in the sub-100-nmrange—have a depth-of-focus (DOF) of <1 μm—that is, extremely flatsubstrate surfaces are needed. Structures which are imaged in rangesabove or below the depth-of-focus appear unclear and exhibit deviationsfrom the theoretical size of the structure. Proceeding from ultra-smoothsubstrates (wafers) whose surfaces are produced by using CMP, the wafershave to be repeatedly planarized if the topography on the disk surfaceexceeds the permitted DOF. This always occurs with the firstmetallization scheme described, if the conducting paths, for example,made of aluminum, which have a thickness of 0.5-0.8 μm, cross orintersect. A planarization of the intermediate level dielectric by meansof CMP provides a remedy. Otherwise, short circuits, interruptedconnections, defective contacts between the planes or finally,reliability problems during the operation of the ICs can appear. The useof the damascene or dual-damascene technology with tungsten passagecontacts or copper conducting paths—that is, the production of engravedconducting paths, automatically leads to planar surfaces during thepolishing of protruding metal, and for this reason, this technology isbeing accepted more and more.

Chemical-mechanical polishing is used beyond the already mentionedapplications also—for example, in the creation of trench isolationbetween the components (shallow trench isolation—STI), in the definitionof the control electrodes in MOS transistors (metal gates), in theproduction of microelectromechanical systems (MEMS), in themanufacturing of hard disks and hard-disk writing/reading heads, and soforth. The CMP brings about both a local and also the totalplanarization of the structured surfaces, comprising the entire wafersurface, by the wearing down of elevated layer parts, until a planesurface is obtained. In this way, it is possible to bring about the nextlayer structure on a plane surface without height differences, and thedesired precision of the structuring and the reliability of thecomponents of the circuit can be attained.

A CMP step is carried out with the aid of special polishing machines,polishing cloths (pads), and polishing agents (polishing slurries). Apolishing slurry is a composition which, in combination with thepolishing cloth, the so-called pad, brings about a wearing down of thematerial to be polished on a wafer or another substrate on the polishingmachine. A wafer is a polished silicon disk on which integrated circuitsare arranged. CMP processes can be used on different materials, which,for example, contain oxide, nitride, semiconducting, or metalcomponents.

In polishing processes, polishing pads and polishing liquids carry outimportant functions. Thus, for example, the polishing pad influences thedistribution of the polishing liquid on the wafer, the transporting awayof the removed material or also the formation of topological features(planarity). Important characterizing features of a polishing pad are,for example, its pore shape and size, its hardness and compressibility.The polishing liquid contains, for example, the necessary chemicals andabrasive materials, dilutes and transports removed material, andinfluences, for example, the removal rates of a CMP process with regardto different materials. Characterizing features of a polishing liquidare, for example, its content of chemicals and abrasive materials withregard to type and quantity, the particle size distribution, theviscosity and colloidal and chemical stability. An overview of thetechnology of the CMP can be found, for example, in J. M. Steigerwald,S. P. Murarka, and R. J. Gutmann, “Chemical Mechanical Planarization ofMicroelectronic Materials,” John Wiley & Sons Inc., New York (1996), B.L. Mueller, and J. S. Steckenrider, Chemtech (1998), pages 38-46, or inR. Waser (Editor), “Nanoelectronics and Information Technology—AdvancedElectronic Materials and Novel Devices,” Verlag Wiley-VCH Weinheim(2003), pages 264-271.

Polishing liquids are typically multicomponent systems consisting ofliquid components and dissolved additives (for example, organic andinorganic acids or bases, stabilizers, corrosion inhibitors,surface-active substances, oxidizing agents, buffers, complexing agents,bactericides and fungicides) and abrasive materials (for example,silicon oxide, aluminum oxide, cerium oxide), dispersed in a liquidmedium, typically water. The concrete composition is determined by thematerial to be polished.

Particularly in polishing steps in which semiconductor layersparticipate, the requirements as to the precision of the polishing stepand thus as to the polishing slurry are particularly great. A number ofvariables with which the effect of the polishing slurry is characterizedserve as an evaluation scale for the effectiveness of polishingslurries. Among these variables are the removal rate—that is, the rateat which the material to be polished is removed, the selectivity—thatis, the ratio of the removal rates of materials to be polished to othermaterials present, and variables for the uniformity of theplanarization. These describe an attained degree of planarization(flatness), an undesired polishing into the material (dishing), or anundesired removal of other adjacent materials (erosion). Among thevariables describing the uniformity of the planarization, however, arealso the uniformity of the remaining layer thickness within a wafer(within-wafer nonuniformity, WIWNU) and the uniformity of wafer-to-wafer(wafer-to-wafer nonuniformity, WTWNU), and the number of defects perunit surface (for example, scratches, surface roughness, or adhesiveparticles).

For the production of the IC, the so-called copper-damascene process isbeing increasingly used (see, for example, “Microchip Fabrication: APractical Guide to Semiconductor Processing,” Peter Van Zant, 4th ed.,McGraw-Hill, 2000, pp. 401-403 and 302-309; “Copper CMP: A Question ofTradeoffs,” Peter Singer, Semiconductor International, Verlag Cahners,May 2000, pp. 73-84; U. Hilleringmann, “Silicon SemiconductorTechnology,” Teubner Verlag, 3rd Edition, 2003). It is in that casenecessary to remove a Cu layer chemomechanically with a polishing slurry(so-called Cu-CMP process), in order to produce Cu conductor paths. Thefinished Cu conductor paths are embedded in a dielectric. Between copper(Cu) and the dielectric, there is a barrier layer, in order to prevent adiffusion of copper, in the long run, into the silicon (Si)-substratematerial, which would result in negative consequences for the efficiencyof the IC. Peculiarities and difficulties result from this structurewith regard to the required polishing techniques. In one typical ICproduction process, copper is deposited on a barrier layer made oftantalum/tantalum nitride. Other metals, their nitrides or silicides canalso be used for the above purpose. In the planarization to be carriedout, it is necessary to remove the excess copper and barrier materialwithout attacking the layer of the dielectric underneath. Influenced byvarious material characteristics of the copper (relatively soft,slightly oxidizable) and the tantalum (relatively hard), special demandsare made of a polishing process. The state of the art for the Cu-CMPprocess is a multistage process. The Cu layer is first polished with apolishing slurry, which guarantees a high Cu removal. Subsequently, asecond polishing slurry is used, in order to remove the protrudingbarrier layer. After the subsequent cleaning steps, a planar surfacewith the shiny polished dielectric and the embedded conducting paths isobtained. For the first polishing step, one uses, for example, apolishing slurry with a high selectivity—that is, in that the removalrate for Cu is as high as possible and for the material of the barrierlayer underneath is as small as possible. The polishing process isstopped automatically as soon as the barrier layer under the Cu isexposed. For the removal of the barrier layer in a second polishingstep, polishing slurries with a high removal rate for the barrier layerare used. The removal rate for Cu is lower than or the same as theremoval rate for the barrier layer. To avoid dishing and erosion, theremoval rate of the dielectric should be on the same order of magnitude.

CMP slurries for the polishing of metal, for example, for the firstcopper polishing step, contain one or more chemical compounds whichreact, for example, oxidize, with the material of the layer to beleveled, wherein afterwards the reaction product, for example, the metaloxide, is removed mechanically with abrasive substances in the slurry oron the polishing pad. Exposed metal is then etched slightly with otherchemical compounds, before, once more, a protective oxide coating isformed and the cycle can begin anew. Removal and the attained planaritydepend on the pressure between the workpiece and polishing pad, on thereactive rate between the two and with chemically dominated processes,on the temperature.

From the state of the art, the use of, for example, silicon oxide,aluminum oxide, cerium oxide, or titanium oxide, as the abrasives inpolishing slurries for the first polishing step is known (see, forexample, WO-A 99/64527, WO-A 99/67056, U.S. Pat. No. 5,575,837, and WO-A00/00567). The disadvantage of polishing slurries based on aluminumoxide is the high degree of hardness of the abrasive, which,increasingly, leads to scratches on the wafer surface. This effect canbe reduced in that the aluminum oxide is produced via gas-phaseprocesses and not via melting processes. In this process, one obtainsirregularly shaped particles which are sintered together from many smallprimary particles (aggregates). The gas phase process can also be usedfor the production of titanium dioxide or silicon dioxide particles.Angular particles scratch, in principle, more than round, sphericalparticles. Particularly, smoothly polished surfaces with roughnesses inthe range clearly below 1 nm, for example, on the dielectric materialsilicon dioxide are attained with round, spherical, colloidal silicondioxide particles (precipitated silicic acid).

A dispersion with abrasive particles and a photocatalytic effect causedby TiO₂ during irradiation with light, for example, ultraviolet light,is known from US 2003/0022502 A1. The photocatalytic effect herebysupports the oxidation of the metal layer to be eliminated and thusimproves the abrasive effect of the dispersion.

A dispersion composition with photocatalytic effect and a mixture ofTiO₂ and Ti₂O₃ as a catalyst is known from U.S. Pat. No. 6,177,026 B1.

The disadvantage of this state of the art is that when using titaniumdioxide corresponding to the state of the art, the size or the sizedistribution of the abrasive particles is not optimal—in particular,there is an excessive number of coarse particles—and therefore eitheronly low removal rates are attained or coarse particles or agglomeratesof the abrasive particles cause scratches, grooves, or irregular removalrates and impair the uniformity and efficiency of the CMP process.Slurries with low friction to avoid shear forces are needed, whichshould prevent any layer delaminations during the polishing, inparticular for the polishing of novel materials with a low dielectricconstant (low-k materials), which consist of doped oxides or nanoporouspolymer materials. Another disadvantage of the state of the art is thetedious and expensive production process of the dispersion particles,which to a particular extent, applies to the production of nanoparticlesfrom gas-phase processes.

In particular, with the intended utilization of the photocatalyticeffect, the variants of titanium dioxide, known according to the stateof the art, do not offer optimal characteristics, for example,sufficient photocatalytic activity.

In contrast to this, the goal of the invention is to prepare acomposition or a material for such a composition, which has a highremoval rate with a simultaneous gentle polishing behavior.

With a composition of the type mentioned in the beginning, the goal isattained in accordance with the invention in that the compositioncontains titanium oxide hydrate particles with the approximation formulaTiO₂*xH₂O*yH₂SO₄, wherein the H₂O content of the titanium oxide hydrateparticles is 0.4-25 wt %, preferably 2-10 wt %, and the H₂SO₄ content is0-15 wt %, preferably 0.1-10 wt %.

Here, the indicated and all subsequently listed weight percent valuesrefer to a sample dried according to ISO 787, Part 2.

Titanium oxide hydrate or titanium oxide hydrate particles are herebyunderstood to mean a titanium oxide-containing material with chemisorbedwater and perhaps H₂SO₄ and/or other inorganic and/or organiccomponents, which can be represented also, in part, with theapproximation formula TiO(OH)₂.

With regard to its suitability for the CMP process, the titanium oxidehydrate shows clear advantages in comparison to traditional titaniumdioxide with only low quantities of chemisorbed water (such ascommercial titanium dioxide pigments).

The determination of the H₂O content of the titanium oxide hydrateparticles can take place according to the following equation:H₂O content (%)=Ignition loss (%)−H₂SO₄ content (%)wherein the ignition loss is the weight loss of a sample dried accordingto ISO 787, Part 2, after one hour of igniting at 1000° C., and theH₂SO₄ content is determined by the analytical determination of thesulfur in the sample dried according to ISO 787, Part 2, and conversionto H₂SO₄.

Approximately, the determination of the H₂O content of the titaniumoxide hydrate particles can also be equated with the ignition loss (in%) after one hour of igniting of the sample dried according to ISO 787,Part 2, at 500° C.

An exact determination of the H₂O content of the titanium oxide hydrateparticles can, however, take place basically after one hour of ignitingof the sample dried according to ISO 787, Part 2 at 1000° C. and a gaschromatographic analysis of the volatile components.

A particularly gentle mechanical stress of the surface to be processedwith a simultaneously sufficiently high abrasivity is produced by theinvention as a result of the high specific surface of titanium oxidehydrate and the small particle size of titanium oxide hydrate withchemical-mechanical polishing. This can be supported also by theutilization of the photocatalytic effect of titanium oxide hydrate.

A performance and operating behavior of the abrasive particles, withregard to the total evaluation of removal rate, planarity, selectivity,and defect density, which is better in comparison to the previous stateof the art, is revealed. A favorable combination of a high removalrate-produced by the catalytic or photocatalytic characteristics of thetitanium oxide hydrate—and gentle abrasion behavior is attained with theproduction process connected with this invention when using thecomposition or with the titanium oxide hydrate particles which are thebasis of this invention.

By means of a purposeful design of the characteristic particlecharacteristics, it is possible to combine a photocatalytic effect withimproved abrasive characteristics, so that it is not absolutelynecessary to add other abrasive materials, aside from those which arethe basis of this invention. This reduces the quantity of expendablematerials and has an economizing effect on resources.

Especially with the intended use of the photocatalytic effect, thetitanium oxide hydrate particles offer an optimal combination ofcharacteristics. In addition to a very large BET surface, titanium oxidehydrate particles offer a high catalytic activity, which can beoptimized with respect to the individual application purpose, by aspecific, easily implemented modification for example, with metals ormetal compounds.

The composition in accordance with the invention is characterized by ahigh abrasivity with a very gentle treatment of the polished surfaces atthe same time.

Furthermore, the composition in accordance with the invention ischaracterized by a high catalytic or photocatalytic activity. This isrelated, on the one hand, to the specific physical characteristics ofthe titanium oxide hydrate particles, but on the other hand, also on thehigh specific surface of the titanium oxide hydrate and on its acidity.Moreover, it is possible to influence or to increase the catalyticactivity with chemical additives, for example, with additives of metalions such as Fe, Co, Ni, V, Mo, Ag, Pd, Ru, Rh. These chemical additivescan be admixed with the titanium oxide hydrate or can be applied to thetitanium oxide hydrate, but they can also be incorporated into thetitanium oxide hydrate by a calcination or tempering process.

In accordance with the development of the invention, it is possible forthe titanium oxide hydrate particles to contain up to 10 wt % otherinorganic and/or organic compounds, preferably up to 3 wt %.

The titanium oxide hydrate particles can be obtained by the hydrolysisof inorganic or organic titanium compounds. Depending on the titaniumcompound and the reaction conditions, different characteristics of thetitanium oxide hydrates are produced thereby.

Preferably, to obtain the titanium oxide hydrate, the production methodfor titanium dioxide according to the sulfate process can be used,which, for example, is described in detail in Industrial InorganicPigments (2nd Edition, Gunter Buxbaum, Editor, Wiley-VCH, 1998).

Therefore, the invention, in its development, provides for the titaniumoxide hydrate to be particles yielded after the hydrolysis in theproduction of titanium oxide according to the sulfate method.

Particularly preferred, is that the titanium oxide hydrate obtainedafter the hydrolysis is freed from adhering impurities, in that it iseither filtered and washed or is also additionally subjected to themethod step of so-called bleaching, a chemical treatment with reducingagents to eliminate trivalent iron.

The large-scale production of titanium oxide hydrate according to thesulfate process for the production of titanium dioxide has the advantageof a constant product quality and constant availability.

Preferably, the composition contains titanium oxide hydrate in afraction of 0.1-30 wt %, preferably 3-20 wt %. The concentration optimalfor the individual application purpose can be easily determined by thespecialist by means of simple experiments.

It may be advantageous to treat the titanium oxide hydrate by acalcining or tempering step, in order to increase the particle size andthe abrasivity or to purposefully modify the catalytic or photocatalyticcharacteristics. In particular, the conversion of amorphous titaniumoxide hydrate into microcrystalline anatase can be advantageous. Thecalcining or tempering step should, however, go only so far that thespecial characteristics of the titanium oxide hydrate are not lost—thatis, the fraction of chemisorbed water (for example, in the form ofhydroxyl groups) may not be smaller than 0.4 wt %, preferably 2.0 wt %,in order to retain a catalytically or photocatalytically reactivesurface of the titanium oxide hydrate.

With the titanium oxide hydrate calcined at high temperatures, thecatalytic or photocatalytic activity, on the other hand, clearlyrecedes, whereas the titanium oxide hydrate is converted to“macrocrystalline” (with a crystal size of >100 nm) TiO₂ (in the anataseor rutile modification) with a content of chemisorbed water of clearlysmaller than 1 wt %. In accordance with the development of theinvention, it is advantageous if the titanium oxide hydrate particleshave an ignition loss of >2 wt %, preferably >6 wt %, at 1000° C. Thisis with an igniting of 1 h at 1000° C. The determination of the ignitionloss takes place thereby on a sample from the titanium oxide hydrateparticles, predried according to ISO 787, Part 2.

In accordance with the development of the invention, it is alsoadvantageous if the titanium oxide hydrate particles have an ignitionloss of >0.8 wt %, preferably >1.2 wt %, with an ignition of 1 h at 500°C. The determination of the ignition loss thereby takes place also on asample from titanium oxide hydrate particles, predried according to ISO787, Part 2.

Preferably, the BET surface of the titanium oxide hydrate is 150-400m²/g, with particular preference 250-380 m²/g, which the invention alsoprovides. The determination of the BET surface takes place thereby,according to DIN 66131, on a sample from the titanium oxide hydrateparticles, degassed and dried at 140° C. for 1 h.

The invention is also characterized in that the average particle size ofthe primary particles of the titanium oxide hydrate is 3-15 nm,preferably 4-8 nm. This is attained, for example, by the precedingmethod steps, through which, in contrast to traditional gas-phaseprocesses, a technically and economically improved production process ismade available for the formation of nanoparticular titanium oxidehydrate-containing abrasive materials.

The primary particles are small, approximately spherical,microcrystalline particles with a lattice-defective anatase structure.The particle size can be determined either by electron microscope orcalculated from the BET surface.

These primary particles form flake-like structures of approximately30-60 nm in diameter which are designated as secondary particles. Thesesecondary particles are very stable, with respect to mechanical andchemical influences. They can be partially destroyed mechanically, onlywith a very high energy use; even chemically, a splitting of thesecondary structure into isolated primary particles is very difficult(see U.S. Pat. No. 5,840,111).

The secondary particles form, in turn, tertiary particles (ca. 1000 nm),which are irregularly (cloud-like) shaped and deform by the use ofmechanical energy, and in contrast to the primary and secondaryparticles, can be partially divided up also with a high mechanicalenergy input. With a particle size determination of the titanium oxidehydrate by means of laser diffraction, only the tertiary particles arevery predominantly detected and measured even with a strong ultrasonicdispersion.

Both the secondary and the tertiary particles are firmly held togetherby van der Waals' forces and electrostatic forces, but are not rigidstructures. Their mode of action with regard to the mechanical stress,as it occurs in the CMP process, can be compared with a flexiblepolishing pad, which is covered with extremely finely divided, abrasiveparticles: on the one hand, microcrystalline primary particles, whichdevelop a mechanical abrasion effect, are present; on the other hand,these primary particles are bound into a stable but neverthelessflexible structure, which makes possible both an efficient forcetransfer from the polishing pad to the surface to be polished and anadaptation of the abrasion effect to the surface texture. The resultfrom this is that exposed areas on the surface to be polished aremechanically abraded more intensely and deeper areas more weakly. Thisstructure of the titanium oxide hydrate particles is particularlyadvantageous, because as a result of the very small primary particles ofthe CMP process, on the one hand, a very smooth surface of themicroelectronic components is produced; on the other hand, however, anefficient force transfer from the rotating polishing disk to the surfaceto be polished takes place due to the binding of the primary particlesinto the secondary particles or tertiary particles. In this way, bothvery smooth surfaces and also good removal rates can be obtained. Thus,the CMP process is influenced in the desired manner by the specificstructure of the titanium oxide hydrate particles.

The titanium oxide hydrate particles for use in a composition accordingto one of claims 1-22 can be produced in good quality, at low cost, bythe hydrolysis of titanyl sulfate solution and the subsequent separationand perhaps cleaning of the titanium oxide hydrate obtained.

In a further development, the invention therefore provides for thetitanium oxide hydrate to be produced by the hydrolysis of titanylsulfate solution, the subsequent separation, and perhaps the cleaning ofthe titanyl oxide hydrate thereby obtained.

With titanium oxide hydrate as it is obtained in the hydrolysis oftitanyl sulfate solution, a particularly advantageous combination ofcharacteristics is present:

On the one hand, this titanium oxide hydrate has very small primaryparticles of microcrystalline anatase, wherein a high photocatalyticactivity and at the same time, a gentle surface treatment are broughtabout. On the other hand, an efficient transfer from the polishing padto the wafer surface can take place because of the secondary particles,wherein, in addition, a mechanical component contributes to an optimalremoval behavior.

The titanium oxide hydrate particles can, for example, be obtained bythe hydrolysis of a sulfuric acid-containing titanyl sulfate solution.Depending on the origin and composition of the sulfuric acid-containingtitanyl sulfate solution, a sulfuric-acid suspension of titanium oxidehydrate during the hydrolysis is obtained which can still containundesired impurities—in particular, heavy metals. As a rule, therefore,one or more cleaning steps are undertaken, in order to free the titaniumoxide hydrate from undesired impurities.

For the highest purity, it is advantageous not to use the large-scalemetal ion-containing, sulfuric acid-containing titanyl sulfate solution,but rather a synthetic sulfuric acid-containing titanyl sulfatesolution, which contains only small quantities of impurities. Theproduction of a highly pure titanium oxide hydrate therefrom can takeplace either analogous to traditional, large-scale processes or withsome differences.

The small content of metal trace elements can have a favorable effect onthe defect density or reliability of the integrated circuits.

It is thereby advantageous also if the titanium oxide hydrate isdeflocculated by the addition of HCl (hydrochloric acid) at least inpart, which the invention also provides for. This deflocculation—thatis, the partial decomposition of the secondary and/or tertiaryparticles—can be attained in a solution strongly acidified byhydrochloric acid by electrical charge reversal of the particle surface.In this way, a de facto more finely divided particle structure isattained which can manifest itself particularly positive on thehomogeneity of the removal or on the attainable surface roughness.

It is also advantageous if the titanium oxide hydrate is present as atransparent sol. This transparent sol from isolated titanium oxidehydrate primary particles has a minimal mechanical removal effect(comparable with a CMP solution without any solids fraction), and can beused, however, for specific CMP processes as a result of thephotocatalytic characteristics of the titanium oxide hydrate.

Such a sol can be produced as described in U.S. Pat. No. 5,840,111.

Furthermore, it is advantageous for the photocatalytic characteristicsif the titanium oxide hydrate contains 20-2000 ppm niobium (Nb),relative to TiO₂, preferably, 50-500 ppm niobium (Nb), which theinvention provides for in a further development.

It is particularly advantageous for the photocatalytic characteristicsif in the titanium oxide hydrate, the molar ratio of niobium to aluminumNb/Al is >1, preferably >10, and/or the molar ratio of niobium to zinc(Nb/Zn) is >1, preferably >10. Such a photocatalytic material or acomposition, in accordance with the invention, with this material ischaracterized by a particularly good photocatalytic effect.

It is also advantageous if the rutile content of the titanium oxidehydrate is less than 10 wt %, preferably less than 1 wt %, since thephotocatalytic characteristics of anatase is, as a rule, more pronouncedthan that of rutile.

It is also advantageous if the titanium oxide hydrate contains 20-2000ppm chloride, preferably, 80-800 ppm. This influences the photocatalyticcharacteristics positively.

It is also advantageous if the titanium oxide hydrate contains less than1000 ppm carbon, preferably, less than 50 ppm, which the invention alsoprovides for. This also influences the photocatalytic characteristicspositively.

An appropriate refinement of the invention is to be found in that thetitanium oxide hydrate contains less than 100 ppm iron, aluminum, orsodium, preferably, less than 15 ppm. In microelectronic applications, alow content of metal ions, such as iron, in polishing liquids favorablyinfluences the reliability of the chemomechanically polished components,under the influence of the composition, in accordance with theinvention. The introduction of contaminations into the substrates, whichnegatively influence the charge carrier service life is minimized orhindered.

It is also advantageous if the titanium oxide hydrate is coated with aninorganic and/or with an organic compound.

Thus, in addition to the abrasive and photocatalytic characteristics ofthe titanium oxide hydrate, the zeta potential, surface morphology,tribological characteristics, and other physicochemical characteristicsof the abrasive particles are purposefully adjusted, depending on therequirement of the substrate to be polished, and thus, for example,positively influence the selectivity, removal performance, orcharacteristics with regard to the post-CMP cleaning.

It is also advantageous hereby if the titanium oxide hydrate is coatedwith noble metals or noble metal compounds. In this way, thephotocatalytic characteristics can also be improved or purposefully,positively influenced.

Usually, the CMP process—with the composition of the invention also—iscarried out at pH values of 9-11 for oxide-CMP (for example, SiO₂) orwith pH values of 3-7 with metal-CMP (for example, copper).

In accordance with another development, the invention, conversely,provides for the composition to have a pH value smaller than 2,preferably, smaller than 1, or a pH value greater than 12, preferably,greater than 13.

An advantageous variant of the invention is found in that thecomposition, in accordance with the invention, with titanium oxidehydrate as the abrasive has a pH value greater than 12, preferably,greater than 13. In contrast to the compositions used according to thestate of the art which contain SiO₂ or Al₂O₃ as the abrasive, thetitanium oxide hydrate in the composition in accordance with theinvention also does not exhibit any solubility with extremely high pHvalues. In this way, the removal rate can be considerably increased, inparticular, with the CMP process on oxide surfaces (for example, SiO₂).

However, even with low pH values smaller than 2, preferably smaller than1, the titanium oxide hydrate exhibits a very high stability. Inparticular, in a solution acidified with hydrochloric acid, the titaniumoxide hydrate (in contrast to SiO₂ or Al₂O₃) in the composition of theinvention does not exhibit an appreciable solubility with extremely lowpH values either. In this way, the removal rate can be considerablyincreased, especially with the CMP process on metal surfaces (forexample, Cu, W, or Ta).

In an advantageous manner, the invention also provides for thecomposition to contain one or more other abrasives and/or solids also.In this way, for example, the selectivity of a polishing liquid can bepurposely adjusted with respect to the substrate surface.

In addition to the preceding, it is, of course, also possible to add, inaddition to titanium oxide hydrate, other solid particles also, withconditions which are particularly suitable for the effectiveness of thephotocatalytic effect, in order to attain the highest possiblemechanical removal rates. A mixture of various components of which thetitanium oxide hydrate acts predominantly (but not only)photocatalytically, whereas other components act chemically ormechanically, can be particularly advantageous.

It can also be advantageous if the composition contains titanium dioxide(TIO₂). In this way, the photocatalytic characteristics of the titaniumoxide hydrate can be combined well with the abrasive characteristics ofTiO2, and positive synergy effects can be attained and utilized.

In a method of the initially designated type, the aforementioned goal isattained in that during the chemical-mechanical polishing, a compositionaccording to one of claims 1-22 is applied on the surface of thecomponent and while polishing, is moved over the surface.

Hereby, the photocatalytic effect of the titanium oxide hydrate or thecomposition can be used in a supporting manner, so that the invention ischaracterized in that during the chemical-mechanical polishing, acomposition according to one of claims 1-22 is subjected to anirradiation with visible and/or ultraviolet light for the initiation andutilization of a photocatalytic effect.

Furthermore, the aforementioned goal is attained by a microelectroniccomponent, in particular, a semiconductor element, and/or a mechanicalcomponent, in particular, microelectromechanical component orsemiconductor element (MEMS), produced according to the precedingmethod.

Also, the aforementioned goal is attained by a chemical-mechanicalpolishing (CMP), which is carried out using a composition according toone of the aforementioned feature combinations, which the invention alsoprovides for. Hereby, it is particularly advantageous if a metal, anelectrically conductive and/or a dielectric structure ischemomechanically polished, which the invention provides for in itsdevelopment.

Finally, it is particularly advantageous to carry out achemical-mechanical polishing using the composition in accordance withthe invention if a copper-containing structure is polishedchemomechanically, which the invention, finally, also provides for.

The invention is explained in more detail below with the aid of someselected examples, wherein the invention is in no way limited to thespecific examples.

EXAMPLE 1 CMP Removal Characteristic with Silicon Dioxide Layers

The removal behavior of the compositions in CMP processes, which are thebasis for this invention, was described by diverse polishing tests,which were all carried out on a Peter Wolters PM200 Gemini CMP clustertool from the Peter Wolters Surface Technologies GmbH, equipped with apolishing machine, brush cleaner, and automatic wafer handling. Assubstrates, 150 mm (diameter) silicon wafers with a coating of 1000 nmSiO₂ (thermally oxidized) were used.

As a polishing pad, a Suba 500 from Rohm & Haas Electronic Materials wasused.

For all polishing processes, the machine parameters summarized in Table1 were used. TABLE 1 Machine parameters of the polishing processes Force900 N Backside pressure wafer-chuck 15 kPas Chuck speed 44 rpm Polishingdisk speed 45 rpm Dispersion flow 180 mL/min

For each dispersion, 3 wafers were polished every 120 s. After eachwafer, the polishing pad was conditioned with a nylon brush. Controlwafers were treated between the individual test dispersions in order torule out or to minimize a falsification of the measurement values byentrainment. The two-fold cleaning of the wafer after the polishing stepwas carried out with the aid of PVA brushes and deionized water. Theremoval performances attained with the dispersions and the nonuniformitywere determined after the polishing and cleaning had been done byreflectometric measurements of the oxide layer thickness with a Sentechspectral photometer.

The titanium dioxide hydrate-containing materials, which are the basisof the invention were tested (unless otherwise specified) in the form ofaqueous dispersions with a solids content of 25 wt % in the pH range of9-10 as polishing liquids. The composition of the polishing liquids andthe polishing results are summarized in Table 2. TABLE 2 Composition andpolishing results of the tested dispersions for SiO₂-CMP. RemovalAverage particle Solids content Rate Non-Uniformity Dispersiondiameter[nm] pH [%] [nm/min] [%] 1-A 6 11.8 25 16 21 1-G 6 1.19 25 9 8.51-H 6 9.92 25 84 9.4 1-J (Comparative 25 10.19 12.5 228 5.2 example)

Dispersion 1-A in accordance with the invention, with titanium oxidehydrate, in the form of relatively soft aggregates as secondaryparticles, shows a low removal performance in comparison to a typicaloxide-CMP process. It may, however, be advantageous to use thisdispersion in accordance with the invention for metal-CMP processes orphotocatalytically reinforced metal-CMP processes. Damage to thepolished surface by particle contamination and formation of scratches isnot observed.

Dispersion 1-G in accordance with the invention shows the lowest removalrate because of the low pH value. Here, the chemical component of theCMP process is still only minor, and the observed removal performancecan be attributed to a purely mechanical fraction. Damage to thepolished surface by particle contamination and formation of scratches isnot observed. Dispersion 1-G contains the titanium oxide hydrate indeflocculated form. Therefore, the use of 1-G as a deflocculatedtitanium oxide hydrate for the metal-CMP area appears advantageous.

Dispersion 1-H in accordance with the invention consists of titaniumoxide hydrate coated with silicon dioxide and exhibits a higher removalrate in comparison to dispersion 1-A, with a simultaneous halving of thenonuniformity. Thus, the removal performance can be advantageouslyinfluenced by the selection of suitable coatings of the titanium oxidehydrate particles. Damage to the polished surface by particlecontamination and formation of scratches is not observed.

Comparison dispersion 1-J contains commercially available pyrogenic TiO₂(Degussa P 25) and exhibits a high removal performance, but causesdamage to the polished surface by particle contamination and formationof scratches. Therefore, the titanium oxide hydrate-containing,investigated dispersions exhibit advantages, during polishing, withregard to the variably adjustable removal rate and in particular, thedefect density (for example, scratches, surface roughness, or adheringparticles), in comparison to the investigated dispersion on the basis ofpyrogenic titanium dioxide (Degussa P25), which corresponds to the stateof the art.

It is obvious that the titanium oxide hydrate-containing dispersions,described here by way of example, behave advantageously with regard tothe post-CMP cleaning and the deficit density on the polished surface.The presented experimental results can be transferred purposefully todifferent surfaces to be polished in an industrial manufacturing step bythe combination with additives and auxiliaries or adaptation of theproduction conditions of the titanium oxide hydrate-containing materials(depending on the desired ratio of chemical, mechanical or(photo)catalytic activity) and by a refined CMP process operation withregard to its removal behavior.

Particularly advantageous is the use of titanium oxidehydrate-containing dispersions, which are the basis of this invention,for the chemical-mechanical planarization of metal substrates, such ascopper.

Furthermore, the use of the polishing liquids as described in thisinvention with titanium oxide hydrate is advantageous for the use ofphotocatalytically aided CMP methods.

1. Composition in the form of a dispersion or a slurry forchemical-mechanical polishing (CMP) in the production of electronic ormicroelectronic components, in particular, semiconductor elements,and/or a mechanical component, in particular, a microelectromechanicalcomponent or semiconductor element (MEMS), wherein the compositioncontains titanium oxide hydrate particles with the approximation formulaTiO₂*xH₂O*yH₂SO₄, wherein the H₂O content of the titanium oxide hydrateparticles is 0.4-25 wt %, preferably 2-10 wt %, and the H₂SO₄ content,0-15 wt %, preferably 0.1-10 wt %.
 2. Composition according to claim 1,wherein the titanium oxide hydrate particles contain up to 10 wt % ofother inorganic and/or organic components, preferably up to 3 wt %. 3.Composition according to claim 1, wherein the titanium oxide hydrateparticles are particles yielded after the hydrolysis in the productionof titanium dioxide according the sulfate method.
 4. Compositionaccording to claim 1, wherein it contains titanium oxide hydrate in afraction of 0.1-30 wt %, preferably 3-20 wt %.
 5. Composition accordingto claim 1, wherein the titanium oxide hydrate particles have anignition loss of >2 wt %, preferably >6 wt % at 1000° C.
 6. Compositionaccording to claim 1, wherein the titanium oxide hydrate particles havean ignition loss of >0.8 wt %, preferably >1.2 wt % at 500° C. 7.Composition according to claim 1, wherein the BET surface of thetitanium oxide hydrate is 150-400 m²/g, preferably 250-380 m²/g. 8.Composition according to claim 1, wherein the average particle size ofthe primary particles of the titanium oxide hydrate is 3-15 nm,preferably 4-8 nm.
 9. Composition according to claim 1, wherein thetitanium oxide hydrate is produced by the hydrolysis of titanyl sulfatesolution, the subsequent separation, and perhaps the cleaning of thetitanium oxide hydrate thereby obtained.
 10. Composition according toclaim 1, wherein the titanium oxide hydrate is deflocculated, at leastpartially, by the addition of HCl.
 11. Composition according to claim 1,wherein the titanium oxide hydrate is present as a transparent sol. 12.Composition according to claim 1, wherein the titanium oxide hydratecontains 20-2000 ppm niobium (Nb), relative to TiO₂, preferably 50-500ppm niobium (Nb).
 13. Composition according to claim 1, wherein in thetitanium oxide hydrate, the molar ratio of niobium to aluminum Nb/Alis >1, preferably >10, and/or the molar ratio of niobium to zinc(Nb/Zn), >1, preferably >10.
 14. Composition according to claim 1,wherein the rutile content of the titanium oxide hydrate is less than 10wt %, preferably less than 1 wt %.
 15. Composition according to claim 1,wherein the titanium oxide hydrate contains 20-2000 ppm chloride,preferably 80-800 ppm.
 16. Composition according to claim 1, wherein thetitanium oxide hydrate contains less than 1000 ppm carbon, preferablyless than 50 ppm.
 17. Composition according to claim 1, wherein thetitanium oxide hydrate contains less than 100 ppm iron, aluminum, orsodium, preferably less than 15 ppm.
 18. Composition according to claim1, wherein the titanium oxide hydrate is coated with an inorganic and/orwith an organic compound.
 19. Composition according to of the precedingclaims claim 1, wherein the titanium oxide hydrate is coated with noblemetals or noble metal compounds.
 20. Composition according to one claim1, wherein it has a pH value of smaller than 2, preferably smaller than1, or a pH value of greater than 12, preferably greater than
 13. 21.Composition according to claim 1, wherein it also contains one or moreother abrasives and/or solids.
 22. Composition according to claim 1,wherein it contains titanium dioxide (TiO₂).
 23. Method for theproduction of an electronic or microelectronic component, in particular,a semiconductor element, and/or a mechanical component, in particular, amicroelectromechanical component or semiconductor element (MEMS), whichis subjected to a chemical-mechanical polishing method (CMP), under theinfluence of a titanium-containing composition in the form of adispersion or a slurry, wherein a composition according to claim 1 isapplied on the surface of the component and while polishing, is movedover the surface.
 24. Method according to claim 23, wherein during thechemical-mechanical polishing, a composition according to claim 1 issubjected to an irradiation with visible and/or ultraviolet light forthe initiation and utilization of a photocatalytic effect. 25.Microelectronic component, in particular, a semiconductor element,and/or mechanical component, in particular, a microelectromechanicalcomponent or semiconductor element (MEMS), produced according to amethod according to claim
 23. 26. Chemical-mechanical polishing (CMP),carried out with the use of a composition according to claim
 1. 27.Chemical-mechanical polishing according to claim 26, wherein a metal, anelectrically conductive and/or dielectric structure, ischemomechanically polished.
 28. Chemical-mechanical polishing accordingto claim 27, wherein a copper-containing structure is polishedchemomechanically.